The present invention relates to the general field of visually coded electrical conductors and cable, more particularly to the field of visually coded armored cable, and even more particularly to a new and improved version of color-coded armored cable.
Visual coding of electrical conductors and cable to distinguish their electrical properties, intended use, or other characteristics has been a long time practice. Such coding has typically used, for example, alpha-numeric stamping, varied marking patterns, or specific colors or color combinations, to respectively distinguish the electrical characteristics, application, or the like, of the conductors or cable. Such coding is represented by industry practices and documented in patents dating back at least as early as the 1900s. Examples of these patents are U.S. Pat. No. 951,147, issued Mar. 8, 1910; U.S. Pat. No. 2,106,048, issued Jan. 18, 1938; U.S. Pat. No. 3,720,747, issued Mar. 13, 1973; and U.S. Pat. No. 5,340,326 (FIG. 8), issued Aug. 23, 1994.
A particular type of cable known as armored cable has been in use for many decades. Metal clad armored cable comprises an elongated outer sheath of metal, primarily for the mechanical protection of the insulated conductors which extend through the inner passageway defined by the sheath. The metallic sheath is typically formed by a helically wound strip with adjacent convolutions overlapping and interlocking with one another to provide a flexible metal conduit that facilitates the electrical conductor installation process and the particular routing of conductors.
Given that visual coding of other type of cable had already become commonplace, it was then not surprising that visual coding, including color coding, of armored cable also became a common practice in the United States and elsewhere. This is reflected not only by industry adoption of color-coding of armored cable at least as early as the 1980s using, for example, paint applied to, or colored jackets surrounding, the cable sheath, but also by many disclosures of such approach in the patent literature.
For example, British patent specifications GB 194,419 (1923); U.S. Pat. No. 1,117,862 (1968); and U.S. Pat. No. 1,432,548 (1976) all disclose visual coding of armored cable. U.S. Pat. No. 4,875,871, issued Oct. 24, 1989, discloses color coding of various modular components of an electrical network including, significantly, color coding of flexible metal clad armored cable (FIG. 17c). A “family” of interrelated patents owned by WPFY Inc., namely U.S. Pat. Nos. 5,350,885; 5,468,914; 5,557,071; and 5,708,235 (re-issued as Re 38,345), all disclose various versions of color-coded armored cable, particularly those in which different patterns of visible indicia, i.e., predetermined arrangements of discrete markings, particularly color, have been selectively applied to the surface of the armored cable sheath. The selective application of the color pattern leaves exposed, as bare metal, preselected portions of the “crowns” and “valleys” of the cable sheath. The result is a difference of visual appearances, or duality of contrast, between the exposed metal portions and the pattern of colored indicia.
Unfortunately, prior color-coding techniques for armored cable, and the resulting color-coded armored cable, have substantial disadvantages associated with them. For example, use of color patterns or other types of visible indicia as the means for color-coding, like that described and claimed in the above-described family of WPFY patents, while admittedly artistic, can be distractions from the primary objective that the color-coding is intended to achieve—namely, the immediate and readily understood “decoding” or identification of the type and application of the particular coded armored cable. Additionally, the requirement that the color coating leave portions of the surface of the metal sheath exposed is not only unnecessary from an electrical standpoint, but results in a needless processing expense and could cause the sheath to be susceptible to corrosion. Furthermore, to the extent that industry has recognized these problems and adopted a solid, continuous, (rather than patterned) color-coding approach, the full benefits and advantages of this approach have not yet been achieved. For example, when using a continuous solid color coating applied to the cable sheath, unless the color coating has a high degree of retention to the surface of the sheath, the full benefit of this approach may not be realized.
It is therefore a principal object of the present invention to provide a new and improved version of color-coded armored cable substantially different from any prior approach, and one that provides an easily identifiable, efficient and durable identification system. It is another object of the present invention to provide an improved color-coded armored cable which avoids the disadvantages of one that has indicia or patterns applied to the outer surface of the metal sheath. It is another object to avoid the disadvantages associated with a color coding technique which requires exposed areas of bare metal on the surface of the cable sheath. It is a still further object of the invention to provide a new and improved version of solid color-coded armored cable, meeting the aforementioned objects.